Aspects of the present disclosure relate generally to telecommunications, and more particularly to techniques for reporting channel feedback in a wireless local area network (WLAN).
The deployment of WLANs in the home, the office, and various public facilities is commonplace today. Such networks typically employ a wireless access point (AP) that connects a number of wireless stations (STAs) in a specific locality (e.g., home, office, public facility, etc.) to another network, such as the Internet or the like. An AP can request that the STA provide channel feedback of a wireless channel to allow the AP to improve quality of communication to the STA. The AP can initiate a request for channel feedback to the STA as a null data packet announcement (NDPA) to indicate sending of a null data packet (NDP) by the AP, which the STA can receive and use to determine the channel feedback. The NDPA can include certain information regarding the requested channel feedback. After sending the NDPA, the AP sends a NDP, which the STA receives and uses to compute a channel feedback matrix by processing one or more subcarriers as received by the STA based on the NDP to determine an associated power, phase shift, etc. of the NDP at the one or more subcarriers. The STA can compress the channel feedback matrix to indicate a set of angles representing a matrix rotation (e.g., Givens rotation) for the one or more subcarriers over a set of spatial streams. The AP receives the compressed channel feedback matrix, and can determine a steering matrix for steering transmissions via transmit antennas to improve beamforming to the STA.